Electromagnetic detection system for parking operation

ABSTRACT

A system which provides an alarm indicative of a presence of an obstacle in a vicinity of a vehicle. The system operates by electromagnetic detection, and generates an oscillating radiofrequency signal. A transmitter transmits the generated oscillated radiofrequency signal to create, all around the transmitter, an electromagnetic radiofrequency near field. A receiver receives the electromagnetic radiofrequency near field. A detector is connected to the receiver and detects a perturbation resulting in a reduction of an oscillation amplitude of the electromagnetic radiofrequency near field, and an indicator indicates the detected perturbation of the received electromagnetic radiofrequency near field. Based on this operation, an obstacle in a vicinity of the vehicle can be detected.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a system able to provide an alarm signalindicative of the presence of any kind of obstacles in proximity of thepart of the vehicle which has to be protected.

The application of this system becomes very usefull during parkingoperation and mainly for protecting the back part of the vehicle themost difficult to control from the driver seat.

2. Discussion of the Background

It is known, in the applicable art, to employ different systems for usein vehicles control during parking operation.

These systems include means vhich detect approaching obstacles bymonitoring with acoustic or view signals in all the cases in which thedirect perception of the driver is difficult or impossible.

It is possible to mention some examples of prior art for use with thesame purpose to which the present invention relates.

For example, U.S. Pat. No. 4,278,962, is based on the use oftransmitting and receiving means of ultrasonic waves. In this case theelectronic system includes one or more transmitting-receivingtransducers mounted outside the vehicle bumper and an electronic unit,electricaly connected to them, which decodes the acoustic wavesreflected by obstacles in proximity of the vehicle and to signalizeapproximately the distance by digital or analogic means.

Such a system is nevertheless not always able to recognize the realdistance between the ultrasonic transdoucer and the detected obstaclebecause the ammount of reflected ultrasonic waves (one of the parameterson which is based the distance measuring system) is dependent on theshape, density and reflective property of the obstacle.

Furthermore the ultrasonic system is unable to detect obstacles whichare closer than 30-40 centimeters owing to the physical limits of thesystem which is based on the measurement of the time employed by theacoustic waves to return after reflection.

It is also known that the detection field, when using an ultrasonicsystem, has a conical shaped configuration and for this reason it is notable to protect, for example, the bumper surface for all its extensionbut only with an angled limitation departing from the acoustictransdoucer. For this reason, in order to obtain a more completeprotection, it is necessary to use more than one acoustic transdoucer.

In addition, the prior art ultrasonic system needs the use of externalsensors (acoustic transdoucers) which are visible and susceptible ofhandling and damagement. Furthermore the ultrasonic system is relativelyexpensive in its components (electronic unit, ultrasonic transdoucers).

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome the problems of theprior art and to provide a practical obstacles detection system, mainlyfor vehicles, of low cost, easy installation, not visible outside thevehicle and able to give an alarm signal when an obstacle is approachingthe part of the vehicle which has to be protected, with the followingbenefits:

Detection of the obstacles approaching the vehicle with absolutecontinuity for all the extension of the part which has to be protected(for example the bumper).

Detection of the obstacles not depending on their physical properties asshape, dimensions, density and reflective propriety.

Continuity of the obstacles detection from the maximum detectiondistance up to the contact without the blind zone (30-40 centimetersbefore the contact) which characterizes the prior art systems.

Increment of the detection sensitivity as the obstacle distancedecreases which guarantees a more prompt alarm signal for very shortapproaching movements in the close proximity.

Low cost.

For this purpose, according to the present invention, theelectromagnetic detection system is characterized in that it employs, inits preferred embodiment, a transmitting-receiving mean consisting oftwo wires or strps of electrical conductive material (antennas) coupledtogether; a means capable of generating an electromagnetic field (nearfield) of radio frequency all around this transmitting-receiving means;a means capable of detecting (demodulate) the variations of saidelectromagnetic field caused by an object which is approaching to saidtransmitting-receiving means; a means giving an acoustic or wiev alarmsignal in presence of such electromagnetic field variation.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, in his preferred embodiment, inmore details with reference to the accompanying drawings, in which:

FIG. 1 is a general block diagram of the apparatus of the preferredembodiment of the invention.

FIG. 2 is an electrical circuit schematic diagram of the apparatus ofthe preferred embodiment of the invention.

FIG. 3 shows an example of automotive installation of the system, objectof the present invention, for use as vehicle parking control in the backside of the vehicle.

FIGS. 4,5 and 6 show respectively the diagrammatic configuration of thesection view, the side view and the upper view of the electromagneticdetection field generated around the car bumper when employing thepreferred embodiment of the present invention used as parking control.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the enclosed drawings, the apparatus employing thesystem object of the present invention is mainly composed, in apreferred embodiment, of two parts: one electronic units M and oneelectromgnetic radio frequency field F. In more detail, in FIG. 1, Atsymbolizes the transmitting antenna connected with the radio frequencyoscillator T and Ar simbolyzes the receiving antenna connected with therevealation device R, A symbolizes the signal amplifier and S theacoustic module for alarm signal.

The electrical circuit of FIG. 2 is a preferred application example ofthe general block diagram of FIG. 1. In it the transmitting-receivingmeans is constituted by two simple coupled electrical wires like, forexample, a Television flat antenna 300 Ohm cable.

In both the drawings is diagrammatically shown with F theelectromagnetic near field which, expanding all around said transmittingantenna At, encloses said receiving antenna Ar which is connected to thesaid revelation unit R where 1 and 2 are, for example, two germaniumdiodes used to demodulate the amplitude variation of the electromagneticsignal captured by the antenna Ar. To said revelation unit R isconnected, through the resistor 3 and the capaciotor 4, amplifier A; thefunction of the resistor and capacitor is to cut continuous componentsof the radio frequency signal in order to transfer, to the amplifier A,or better, to the first operational amplifier 5, only the alternatecomponent of the signal caused by the variation of the electromagneticfield F. In this manner it is possible to obtain a self-adjustingcondition of the circuit in order that slow variations of someparameters (external temperature, power supply voltage, length andcoupling characteristic of antennas) are not affecting the reliabilityof the electronic circuit.

Furthermore said amplifier A includes, beside few resistors andcapacitors, the resistor 6 which applies the revealed signal to thesecond operational amplifier 7 for a further amplification. Saidamplifier A is connected to the acoustic module S which includes thetransistor 8 which provides the output to the acoustic transducer 9 forthe audible alarm signal.

Said transmitting antenna At is connected to the said radio frequencyoscillator T which, in this example, mainly comprises one transistor 10and one coil 11 in order to generate radio frequency oscillations, e.g.below 150 KHz, coupled to the second coil 12, but may alternatively beany kind of radio frequency free-oscillator.

The electronic unit now described is encapsulated in a small size modulewhich can be easily arranged, for example, inside the vehicle close tothe reverse gear lamp from which it can receive the power supply of 12Vdc during the parking operation (see FIG. 3).

To said module will be connected to the two antennas At and Ar whichwill be easily arranged, for example, inside the plastic bumper. To thispurpose it could be used a two wire electric cable where the distancebetween the two wires may be possibly not less than 4-5 millimeters.

According to the present invention, this preferred embodiment of thesystem installed on a vehicle ensures, when the circuit is switched on,the generation of a near electromagnetic field F all around thetransmitting antenna At. Due to the proximity of the conductive materialof the vehicle and to the particular arrangement of the antenna At, thespace configuration of this electromagnetic near field appears asdiagrammatically shown in FIGS. 4,5,6. The receiving antenna Ar that, inthis case, is immerged in said electromagnetic field will receive thisradio frequency signal of constant amplitude. When any object, with theonly exclusion of substances with very low electrical conductivity(glass, ceramic, plastic with clean surfaces), enters thiselectromagnetic field, this generates a field parameters perturbationand consequentely causes a reduction of the oscillations amplitudewhich, in this particular case, will be detected by the receivingantenna Ar and applied to the revealation module R and transformed,through the said amplifier A, in an audible alarm signal produced by thesaid acoustic module S.

It is to be appreciated that the foregoing description is of a preferredembodiment of the invention which can be modified in various wayswithout departing from the spirit and scope of the invention which couldwidely be changed in its circuitry characteristics and in itsapplications field.

For example, the system object of the present invention could beutilized as a body detector for use in walking-through access controlsdevices, as a proximity sensor for use in close/open doors, to actuateillumination or alarm systems and furthermore, with the use of antennacables of appropriate length, for perimetral protection systems.

Furthermore, with appropriate improvements of the basilar electroniccircuit, it could be used as a warning device for predeteminedapproaching distances in vehicular or objects movement.

I claim:
 1. An electromagnetic detection system for detecting obstaclesduring a vehicle parking operation, comprising:a generating means forgenerating an oscillating radiofrequency signal; a transmitting meansconnected to the generating means and receiving the radiofrequencysignal and for transmitting the radiofrequency signal to create, allaround said transmitting means, an electromagnetic radiofrequency nearfield; a receiving means for receiving the electromagneticradiofrequency near field; a detecting means connected to the receivingmeans for detecting a perturbation resulting in a reduction ofoscillation amplitude of said electromagnetic radiofrequency near fieldreceived by the receiving means; and an indicator means connected to thedetecting means for indicating the detected perturbation of the receivedelectromagnetic radiofrequency near field.
 2. The electromagneticdetection system as claimed in claim 1, wherein the transmitting andreceiving means are formed by two wires of electrical conductivematerial, used as antennas, coupled together.
 3. The electromagneticdetection system as claimed in claim 1, wherein the means for generatingthe radiofrequency signal includes an electronic oscillator coupled tothe transmitting means.
 4. The electromagnetic detection system asclaimed in claim 3, wherein the electronic oscillator comprises onetransistor, connected to a first coil, which generates a radiofrequencyoscillation which is inductively transferred to a second coil connectedto the transmitting means.
 5. The electromagnetic detection system asclaimed in claim 1, wherein the detecting means comprises a revealationunit coupled to the receiving means.
 6. The electromagnetic detectionsystem as claimed in claim 5, wherein the revealation unit comprises tworevealation diodes which demodulate the electromagnetic radiofrequencysignal received by the receiving means.
 7. The electromagnetic detectionsystem as claimed in claim 1, wherein the detecting means comprises anacoustic transducer.
 8. The electromagnetic detection system as claimedin claim 5, wherein the detecting means comprises an electronicamplifier comprising first and second operational amplifiers.
 9. Theelectromagnetic detection system as claimed in claim 8, furthercomprising a resistor and a capacitor connected between said revealationunit and said amplifier to give a self-adjustment to the detecting meansto avoid instability or malfunctioning due to changes in externaltemperature and voltage supply.
 10. The electromagnetic detection systemas claimed in claim 1, wherein each of the generating means,transmitting means, receiving means, detecting means and indicator meansare encapsulated in a module electrically connected to a reverse gearlamp for power supply.
 11. The electromagnetic detection system asclaimed in claim 5, wherein the revealation unit comprises tworevealation diodes which demodulate the electromagnetic radiofrequencysignal received by the receiving antenna.
 12. An electromagneticdetection system for detecting obstacles during a vehicle parkingoperation comprising:a generator generating an oscillatingradiofrequency signal; a transmitting antenna connected to the generatorand receiving the radiofrequency signal and transmitting theradiofrequency signal to create, all around said transmitting antenna,an electromagnetic radiofrequency near field; a receiving antennareceiving the electromagnetic radiofrequency near field; a detectorconnected to the receiving antenna and detecting a perturbationresulting in a reduction of oscillation amplitude of said radiofrequencynear field received by the receiving antenna; and an indicator connectedto the detector and indicating the detected perturbation of the receivedelectromagnetic radiofrequency near field.
 13. The electromagneticdetection system as claimed in claim 12, wherein the transmitting andreceiving antennas are formed by two wires of electrical conductivematerial coupled together.
 14. The electromagnetic detection system asclaimed in claim 12, wherein the generator includes an electronicoscillator coupled to the transmitting antenna.
 15. The electromagneticdetection system as claimed in claim 14, wherein the electronicoscillator comprises one transistor, connected to a first coil, whichgenerates a radiofrequency oscillation which is inductively transferredto a second coil connected to the transmitting antenna.
 16. Theelectromagnetic detection system as claimed in claim 12, wherein thedetector comprises a revealation unit coupled to the receiving antenna.17. The electromagnetic detection system as claimed in claim 12, whereinthe detector comprises an acoustic transducer.
 18. The electromagneticdetection system as claimed in claim 16, wherein the detector comprisesan electronic amplifier comprising first and second operationalamplifiers.
 19. The electromagnetic detection system as claimed in claim18, further comprising a resistor and a capacitor connected between saidrevealation unit and said amplifier to give a self-adjustment to thedetector to avoid instability or malfunctioning due to changes inexternal temperature and voltage supply.
 20. The electromagneticdetection system as claimed in claim 12, wherein each of the generator,transmitting antenna, receiving antenna, detector and indicator areencapsulated in a module electrically connected to a reverse gear lampfor power supply.
 21. An electromagnetic detection system for detectingobstacles during a vehicle parking operation, comprising:a generatorgenerating an oscillating radiofrequency signal; a transmitting antennaconnected to the generator and receiving the radiofrequency signal andtransmitting the radiofrequency signal to create, all around saidtransmitting antenna, an electromagnetic radiofrequency near field; areceiving antenna receiving the electromagnetic radiofrequency nearfield; a detector connected to the receiving antenna and detecting aperturbation resulting in a reduction of oscillating amplitude of saidelectromagnetic radiofrequency near field received by the receivingantenna; and an indicator connected to the detector and indicating thedetected variation in the amplitude of the received electromagneticradiofrequency near field.
 22. The electromagnetic detection system asclaimed in claim 21, wherein the transmitting and receiving antennas areformed by two wires of electrical conductive material coupled together.23. The electromagnetic detection system as claimed in claim 21, whereinthe generator includes an electronic oscillator coupled to thetransmitting antenna.
 24. The electromagnetic detection system asclaimed in claim 23, wherein the electronic oscillator comprises onetransistor, connected to a first coil, which generates a radiofrequencyoscillation which is inductively transferred to a second coil connectedto the transmitting antenna.
 25. The electromagnetic detection system asclaimed in claim 21, wherein the detector comprises a revealation unitcoupled to the receiving antenna.
 26. The electromagnetic detectionsystem as claimed in claim 25, wherein the revealation unit comprisestwo revealation diodes which demodulate the amplitude of theelectromagnetic radiofrequency signal received by the receiving antenna.27. The electromagnetic detection system as claimed in claim 21, whereinthe detector comprises an acoustic transducer.
 28. The electromagneticdetection system as claimed in claim 25, wherein the detector comprisesan electronic amplifier comprising first and second operationalamplifiers.
 29. The electromagnetic detection system as claimed in claim28, further comprising a resistor and a capacitor connected between saidrevealation unit and said amplifier to give a self-adjustment to thedetector to avoid instability or malfunctioning due to changes inexternal temperature and voltage supply.
 30. The electromagneticdetection system as claimed in claim 21, wherein each of the generator,transmitting antenna, receiving antenna, detector and indicator areencapsulated in a module electrically connected to a reverse gear lampfor power supply.